SBES Distinguished Lecturer Series – March 6

March 6, 2014, 11-12, 310 Kelly (ICTAS)/WFU: 151 Biotech Bldg./VTCRI: R2139

Dr. Robin Queen

Assistant Professor, Department of Orthopaedic Surgery, Duke University Medical Center

Optimizing Life Long Function Following Surgical Intervention

Orthopaedic surgical intervention and post


operative return of function are vitally important to longterm health and function. Currently the postsurgical management of orthopaedic patients is not based on objective measures of function and ability; instead the clinical decisions that are made are based solely on surgeon experience and the time since surgery. Through this talk we will explore what is currently known about postoperative function following a variety of orthopaedic surgical interventions including joint replacements and anterior cruciate ligament (ACL) reconstruction, followed by a discussion of potential objective measures of function and ultimately how to improve longterm health and improve mobility in these patient populations.

In the first half of the talk, I will discuss previous work we have completed examining lower extremity function and loading patterns following these various surgical procedures. Recent work at the Michael W. Kzyzewski Human Performance Lab at Duke University has shown that following surgical intervention significant side-to-side asymmetries exist with regards to lower extremity gait mechanics independent of the surgical population that is being studied. This work has allowed us to begin asking questions about how to better quantify function in the clinical setting and how those measurements are related to threedimensional gait assessment. In addition through this work, we have begun to ask questions about how to improve function through additional, non-surgical interventions as well as identifying way to prevent secondary injuries following surgery. The goal of this work and this talk is to being to discuss method for improving longterm joint function and activity level following orthopaedic surgical interventions and to explore ways of keeping people healthy and active as they age.

Virginia Tech – Wake Forest University School of Biomedical Engineering and Sciences

317 ICTAS, Stanger St., (0298) Blacksburg, Virginia 24061 • 540-231-8191 •

SBES Distinguished Lecturer Series, March 4

March 4, 2014, 11-12:15, 310 Kelly (ICTAS) /WFU: Biotech Bldg./VTCRI: R2139

Biological Laser Printing (BioLP) of Microvascular Cells onto Composite Hydrogel Biopapers

Dr. Bradley Ringeisen,

Dr. Bradley Ringeisen

Head, Bioengry and Biofabrication,

U.S. Naval Research Laboratory

Defense Threat Reduction Agency (DTRA)

Science & Technology Manager

Diagnostics and Disease Surveillance Division


Two major challenges in tissue engineering are mimicking the native cell cell arrangements of tissues and maintaining viability of threedimension (3D) tissues thicker than 200μm. Cell printing and prevascularization of engineered tissues are promising approaches to meeting these challenges. We suggest that both challenges could be addressed by printing 2D patterns of vascular cells onto biopaper substrates. Composite biopapers made of a mechanically supportive polymer scaffold and extracellular matrix-like hydrogel could sustain differentiation and network formation of printed vascular cells, while enabling transfer and stacking of individual biopapers to form thick 3D constructs. We have used several different polymer and hydrogel materials to make composite biopapers including polylactidecoglycolide (PLGA), polydimethylsiloxane (PDMS), MatrigelTM and collagen. Biological laser printing (BioLP) was then used to print patterns of vascular endothelial cells onto the biopapers. The vascular cells differentiated postprinting, stretching to form networks that retained the printed structure as well as forming smaller spontaneous outgrowths. After the onset of vascular differentiation, the biopapers were stacked, cultured and observed with confocal microscopy. Interlayer boundaries were defined with fluorescent beads so that cell migration and networking could be observed between layers. Additional experiments were performed to move towards a 3D brain model by printing vascular cells onto biopapers preseeded with astrocytes. These results demonstrate the feasibility of stackable biopapers as a way to build 3D vascularized tissues with a 2D cell printing technique.

Dr. Bradley Ringeisen is Head of the Bioenergy and Biofabrication Section at the U.S. Naval Research Laboratory (NRL). He is currently on loan to the Defense Threat Reduction Agency (DTRA) Joint Science and Technology Office (JSTO) as a science and technology manager in the Diagnostics and Disease Surveillance Division. He has been tasked as the Project Lead for DTRA/JSTO’s 24 month diagnostics challenge, which is a program that will demonstrate the linkage of point


ofcare/pointofneed diagnostic devices with an informaticsbased, biosurveillance ecosystem.

I will also discuss two projects that are beginning this year in my laboratory. We are engineering two 3D tissue models (lung and blood


-brain-barrier) for in vitro infection and diagnostic biomarker discovery experiments. Aerosolized Burkholderia pseudomallei will be exposed to the lung model while Venezuelan equine encephalitis virus (VEEV) will be exposed to the blood-brain-barrier model. Each model will utilize stacked biopaper and cell printing approaches. A second program will engineer an active acute care covering to stabilize wounds. This project will be developing autonomous materials with bioactive properties including antimicorbials, hemostasis agents and dynamic shape. We are searching for qualified postdoctoral candidates to work on these projects, and I will be available after the seminar to discuss potential opportunities.

During his postdoctoral position, Dr. Ringeisen performed the first successful laser induced forward transfer printing experiment on a living cell. He was hired as a research chemist at NRL in 2002 and currently maintains a six member research group. This group has a wide range of research interests that include the study of microbial extracellular electron transfer, biofuel production, the bio/nano interface, stem cell/material interactions as well as cell and tissue printing for medical and diagnostic applications.

Virginia Tech – Wake Forest University School of Biomedical Engineering and Sciences 317 ICTAS, Stanger St., (0298) Blacksburg, Virginia 24061 • 540-231-8191 •

Hassan Aref Memorial Lecture & Fall Fluid Mechanics Symposium Invited Lecture*

Sap Flow and Sugar Transport in Plants

Thursday, November 21, 2013

11:00-12:00, Assembly Hall, The Inn

Dr. Tomas Bohr

Technical University of Denmark

 Plants have highly effective vascular systems, which can transport fluid over large distances. The xylem system carries water from the roots up to the leaves and the phloem system carries sugar solutions from sources (leaves) to sinks (roots, fruits etc.) and thus provides the necessary material for growth. There are many important fluid dynamical problems connected with these flows, and I shall discuss some of them. In the 1920’ies, Ernst Münch proposed that sugar transport in the phloem is driven by passive osmotic pressure gradients generated by loading and unloading sugar into the phloem tubes (sieve elements) of the leaves. It has been strongly debated whether this hypothesis can actually account for long distance translocation, e.g., from canopy to root of a large tree. In the lecture, I will argue that optimization of the efficiency of the sugar transport leads to a universal scaling of the width of the phloem tubes with the loading (leaf) length and the translocation (stem) length in plants. These predictions have been tested for plants ranging from 10 cm herbacious plants to 60 m trees – both hardwood and conifers – and provide the first quantitative test of Münch’s ideas. For both the xylem and the phloem, the leaves provide the driving force for the sap flow, and I shall discuss current ideas how this complex feat is accomplished.

The lecture is partly based on recent papers:

K. H. Jensen, J. Lee, T. Bohr, H. Bruus, N. M. Holbrook & M. A. Zwieniecki: Optimality of the Münch mechanism for translocation of sugars in plants, Journal of the Royal Society Interface 8, 1155–1165 (2011)

K. H. Jensen, T. Bohr & H. Bruus:  Osmotically driven flows in microchannels separated by a semipermeable membrane, Lab on a Chip 9, 2093-2099 (2009)

K. H. Jensen, J. Liesche , T. Bohr & A. S. Schulz: Universality of phloem transport in seed plants, Plant, Cell & Environment 35, 1065-1075 (2012)

K. H. Jensen, K. Berg-Sørensen, S. Friis & T. Bohr: Analytic solutions and universal properties of sugar loading models in Münch phloem flow, Journal of Theoretical Biology 304, 286-296 (2012)

K.H. Jensen, D.L. Mullendore, N.M. Holbrook, T. Bohr, M. Knoblauch & H. Bruus: Modeling the hydrodynamics of phloem sieve plates, Frontiers in Plant Science 3, article 151 (2012)

L. S. Haaning, K. H. Jensen, C. Hélix-Nielsen, K. Berg-Sørensen & T. Bohr: Efficiency of osmotic pipe flows, Physical Review E 87, 053019 (2013)

*This is a joint seminar co-sponsored by the Department of Engineering Science and Mechanics, the Department of Mechanical Engineering, and the MultiScale Transport in Environmental and Physiological Systems (MultiSTEPS) program.

Renee Pietsch’s To Fly or Not to Fly Article

Teaching Advanced Secondary School Students about Principles of Flight in Biological Systems’ has been accepted for publication in the Journal of Biological Education. Renee is the first author on the paper, along with Cindy Bohland at the Roanoke Valley Governor’s School.  This work came out of her MultiSTEPs rotation in David Schmale’s lab. What a great way to demonstrate the added value of the rotations!

MultiSTEPS trainee Renee Pietsch featured in VT News

High school biology students learn about the physics of flying by studying flight paths of animals and microbes

A flight lab for biology students at the Roanoke Valley Governor’s School was developed by Renee Pietsch, a MultiSTEPS trainee in biological sciences, while working with Dr. David Schmale, an associate professor of plant pathology, physiology, and weed science, during one of her MultiSTEPS research rotations.